by Paul A. Baker, Sherilyn Claire Fritz, Cleverson Guizan Silva, Andrea Marzoli

The Amazon/Andes of tropical South America is a key region on Earth, and its rainforests host over half of all terrestrial plant species. The forests and their biota have evolved together with the physical landscape, closely linking processes in the Earth's interior with surface climate and landscapes, ecosystems, and biodiversity. The proposed Trans-Amazon Drilling Project will address fundamental questions about the geologic and biotic evolution of the Amazon, focusing on (1) how Cenozoic climate and geologic history, including uplift of the Andes and development of the Amazon fluvial system, influenced the origins of the Amazon rainforest and its incomparable biodiversity; and (2) the origin of the Amazonian “Pentecaua” diabase sills, one of Earth’s largest intrusive complexes, and the impacts of this intrusion on the atmospheric gas composition and mass extinction at the Triassic/Jurassic boundary. These goals require long sedimentary records, which, in most of the Amazon region, can only be obtained by drilling. We propose to drill the entire Cenozoic sequence in five continental sites in four different ancient sedimentary basins that are aligned along the modern Amazon River and that transect the entire near-equatorial Amazon region of Brazil, from the Andean foreland to the Atlantic Ocean. The transect of sites is essential for distinguishing basin-wide and continental-scale patterns of climate, landscape, and biotic evolution; evaluating questions about west-to-east gradients and hydrologic connectivity; and correlating the continental strata with a site dated using marine biostratigraphy. In addition, in the Amazonas and Solimões Basins, we propose to drill both the Cenozoic sedimentary sequence and the entire 1100-1200 m thick underlying diabase sequence along with its interbedded host meta-sediments. Drill sites have been chosen that are all near large navigable rivers of the Amazon or roads that are easily accessible from these rivers. This transect, coupled with proposed IODP sites on the Amazon continental margin, will span 40oW to 73oW, thus encircling nearly 10% of Earth’s equatorial circumference. We believe that this work will provide transformative understanding of Amazonian geological and biotic evolution that addresses important and long-standing questions about the linkages between the geophysical environment and its biotic history.

• This project will investigate the geologic evolution of the entire near-equatorial Amazon region of Brazil, from the Andean foreland to the Atlantic Ocean margin, and the impact of that history on biotic evolution at regional to global scales. In a transect of five continental drilling sites, we propose to,
• (1) document the assembly of Amazon plant diversity across the entire Amazon Basin throughout the entire history of the angiosperm-dominated megathermal forests,
• (2) determine how the evolution of the physical environment, including climate, tectonism, and landscape change, has shaped the generation and distribution of neotropical plant diversity and the origins of its species and,
• (3) determine the origins of the Triassic-Jurassic Amazonian sills and the global environmental impact of the >106 km3 of mafic magmatic intrusions in the Amazonian basins that form the major part of the end-Triassic Central Atlantic magmatic province (CAMP), one of the greatest large igneous provinces (LIPs) of Earth history.

Amazon, Biodiversity, Brazil, Central Atlantic Magmatic Province, Microbiology, Rain Forest, South America

Latitude: -7.72650, Longitude: -72.64622